This is an R21 application proposing novel translational investigations into neuroimmune and sensory dysregulation in patients with Chronic Fatigue Syndrome (CFS), to be performed in parallel with guiding animal model research also directed by our research group. The principal symptom of CFS is severe persistent fatigue unrelieved by rest, with a worsening of fatigue and pain symptoms after exercise or stress that persists more than 24 hours. To date, the neural, endocrine, and cytokine alterations that underlie this excessive pre- and post-exertion fatigue and pain are not well-defined, but some biomarker alterations appear to differ in subsets of CFS patients, indicating a heterogeneous disorder. Novel on-going research in mouse models directed by Dr. Alan Light reinforces the potential importance of ATP and recently identified sodium channels that respond to ATP and lactic acid in post- exertional fatigue and muscle pain (Acid Sensing Inward Current or ASIC3, P2X5 and TRPV1 receptors). Prior clinical research by Dr. Kathleen Light indicates adrenergic and cytokine response dysregulation during stressors in CFS patients vs. healthy controls, and between patients with CFS vs. fibromyalgia (FMS). Thus, the current translational R21 includes two related pilot studies that can be completed in 2 years that will lay the groundwork for a later full investigation. Pilot Study 1 proposes to assess coordinated patterns of these potentially dysregulated biomarkers in 40 CFS Patients vs. 40 Controls matched for age, sex, weight and sedentary lifestyle. Responses will be repeatedly assessed, before, during and immediately after mental exertion and physical exertion and 24 hours after exercise. Biomarkers include indexes of cardiovascular adrenergic activity (heart rate (HR) variability, HR and blood pressure (BP) reactivity to stress, and total vascular resistance), adrenomedullary (epinephrine and norepinephrine), adrenocortical (cortisol and ACTH), and ten pro- and anti-inflammatory cytokines/immune markers, measured by multiplexed fluorescent microsphere immunoassay of serum levels and by quantitative expression (via real-time PCR) of mRNA. Real-time PCR will also be used to measure group differences and exertion-related changes in expression of alpha- and beta-adrenergic, ASIC, TRPV and P2X receptors. Patterns of biomarker changes will be related to concurrent changes in the patient self-reported levels of fatigue and pain. In Pilot Study 2, we propose to use a powerful Utah resource, the Utah Population Database, to explore the familial/genetic component of CFS (with and without comorbid FMS). Biogeneticist Dr. Lisa Cannon-Albright will employ two methodologies developed for use with the Utah genealogy resource; a test of the hypothesis of excess relatedness among patients, and estimation of relative risks in close and distant relatives. Significant findings of familiality will provide necessary pilot evidence supporting the importance of a search for the predisposition genes involved, and will identify high-risk pedigree resources that could be used in a later search for predisposition loci, or in specific medication or candidate gene studies. Together, these two pilot projects will provide a potentially invaluable initial test of new directions in both neuroimmune and genetic biomarkers that will add to knowledge about the causes and progression of CFS. [unreadable] [unreadable] [unreadable]